Vane spring



April 9, 196s E, E. BURNETT VANE SPRING Filed Jan. 2l, 1966 INVENTOR ELM/:7? B. BIJ/PNE T 7' United States Patent 3,376,825 VANE SPRING Eimer B. Burnett, Monroeton, Pa., assigner to Ingersolland Company, New York, NSY., a corporation of New ersey Filed Jan. 21, 1966, Ser. No. 522,158 7 Claims. (Cl. 103-136) ABSTRACT OF THE DISCLOSURE speeds, the vane is held against the cylinder wall by centrifugal force.

This invention relates to rotary vane-type fluid machines such as motors or pumps and more particularly to vane springs for such motors or pumps.

The big problem with prior vane springs has been the short life of springs due to fatigue failure caused =by the high number of spring cycles in a short number of motor operating hours.

It has been discovered that the only time a spring is needed to force the vanes of a vane-type tluid motor against the inner wall of the power chamber is when the motor is just starting up or is operating far below normal operating speed. When the motor is operating at normal speed, centrifugal force is sufficient to sealingly engage the vane against the inner wall of the power chamber and the spring becomes unnecessary and undesirable.

It is therefore the object of this invention to prolong the life of a vane spring in a vane type motor or pump yby decreasing the amount of cycling of the spring during normal operation.

Generally, the above object is carried out by providing a spring for a vane type motor or pump which will flatten against the vane due to centrifugal force acting on the spring at a rotational speed below normal operating speed thereby increasing spring life.

This and other objects will become apparent from the following description and claims.

The novel vane spring of this invention will be described in detail in connection with a reversible vane-type motor but is equally applicable to a pump or unidirectional uid motor of the vane type.

In the drawings:

FIG. 1 is a longitudinal axial section through a reversible vane-.ype fluid motor;

FIG. 2 is a transverse section of the motor on a line 2*2 of FIG. 1;

FIG. 3 is an enlarged fragmentary portion similar to FIG. 1 with the vane spring as it would appear if the motor were at normal operating speed.

Referring to the drawings, the reversible iluid motor comprises a housing generally indicated at 1 which includes a hollow cylindrical member 2 and end walls 3 and 4. There are uid inlet ports 5 and 6 and an exhaust port 7. Within the housing there is a cylindrical wall insert 8 forming a power chamber 22 which has inlet ports 9 and 10 and exhaust ports 11.

A rotor 12 with a power take off 13 is eccentrically mounted within the housing and between bearings 14 and 15. The rotor 12 is provided with a plurality of radial slots 16 each having a vane 17, which sealingly engages the internal wall of the power chamber, slida-bly positioned within these slots. A bow spring 18 is positioned Cil within each slot 16 between the vane and the end Wall 19 of the slot and forces the vane into sealing engagement with the internal wall 25 of the power chamber 22 when the motor is stopped or operating at speeds substantially below normal operating speed. There is a pocket 23 in each Vane 17 into which the vane spring flattens when it is flexed. v

The motor is conventional. This invention relates to a novel vane spring. The vane spring 18 has a uniform crosssection throughout its entire length and is designed to be sniciently strong so that when the rotor is at rest, or when the rotor is running at a speed substantially below normal operating speed, the vane spring will bias the vane outwardly into sealing engagement with the internal surface of the power chamber. The spring is suiiciently weak so that when the rotor is running at normal operating speed, centrifugal force will cause the spring to flatten or collapse and become inelfective for biasing the vane outward.

Each bow spring 18 has arcuate upwardly turned ends 20 which engage the vane when the motor is at rest, as shown in FIG. 1. The center portion 21 of the spring engages the end wall 19 of the slot 16 when the motor is at rest. When the motor is at normal operating speed, the spring will lie flat against the vane in the manner shown in FIG. 3.

In choosing a spring for a particular motor, a spring which will provide sufiicient force to cause the vane to sealingly engage the inner Wall of the power chamber is chosen. To determine whether this spring will flatten at a speed less than normal operating speed, use the formula:

n=r.p.m. W=the weight of the spring in pounds F :the force required to flatten the spring in pounds R=radius to the center of mass of the spring in feet The general operation of the vane rnotor is conventional and need not be described except with regard to the novel vane springs.

When the motor is at rest or running at a speed far below normal operating speed, the springs 18 bias the varies 17 outwardly against the inner wall of the power chamber. As the motor approaches normal operating speed centrifugal force takes over for the spring and provides sufficient force to cause the vanes to sealingly engage the inner wall of the power chamber. In addition, the centrifugal force acts on the bow springs and causes them to flatten against the vane as shown in FIG. 3. In most cases this will occur at a speed considerably below normal operating speed. As a result, when the motor is at or near normal operating speed, the spring no longer continues to cycle. Because there is no cycling, at operating speed, spring life will be greatly increased.

Although the invention has been described in use with a rotary vane-type motor, it may be used equally well in a rotary vane-type pump.

The above description is only an illustration of a preferred embodiment, and the invention is limited only by that which is within the scope of the appended claims.

What is claimed is:

1. In a rotary fluid machine such as a motor or pump, a housing having a generally cylindrical bore, an inlet port, an outlet port and a rotor eccentrically mounted in said bore, said rotor having a slot, means positioned within said slot for engaging the internal wall of said bore and spring means sufficiently strong to be effective to bias said engaging means outwardly when said rotor is running substantially below normal operating speed and suiciently weak to be rendered ineffective for biasing said engaging means outwardly at the normal operating speed of said rotor; said spring means being rendered ineffective by centrifugal force causing it to collapse,

2. The apparatus of claim 1 wherein said spring means is a bow spring.

3. The apparatus of claim 2 wherein said bow spring has arcuate, upwardiy turned ends.

4. The apparatus of claim 3 wherein the bow spring is positioned between the engaging means and the end wall of said slot.

5. The apparatus of claim 1 wherein the spring means is a bow spring and the center portion of said bow spring engages the wall of said slot and the ends of said bow spring engage the engaging means when the rotor is at rest.

6. The apparatus of claim 5 wherein the means for engaging the internal Wall of said bore are vanes, said vanes having pockets for receiving said bow spring means.

7. The apparatus of claim 1 wherein said Spring means is uniform in cross-section throughout its entire length.

References Cited UNITED STATES PATENTS 49,391 8/1865 Durre 91-140 3,118,595 1/1964 Fuhrmann 230-152 XR 3,152,552 10/1964 Frenzel 130-136 XR 3,268,157 8./1966 Frenzel 230-145 3,286,912 11/1966 Tado 230-145 u DONLEY J. STOCKNG, Primary Exan'zlzer. 0

T. R. HAMPSHIRE, Assistant Examiner'. 

